DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3 -NRC INTEGRATED INSPECTION REPORT

The NRC sent a letter dated January 25, 2012 to Exelon explaining the Dresden Violations.

Violation #1: A violation of 10 CFR Part 50, Appendix B, Criterion V, “Instructions, Procedures, and Drawings,” was identified on October 24, 2011, when two electrical maintenance technicians performing a clearance boundary safety verification opened a Bus 23 potential transformer (POT) fuse drawer causing an undervoltage load shed signal that resulted in the inoperability of the control room emergency ventilation (CREV) air conditioning system. Corrective actions taken included an electrical maintenance department clock reset and stand down to discuss the event and consequences of taking actions in the plant without proper guidance. Further licensee planned corrective actions include presenting to Operations and the Configuration Control Committee the possibility of installing robust barriers or locking devices on bus POT installations.

The inspectors concluded that the finding had a cross-cutting aspect in Human Performance-Work Practices. The licensee staff involved in the event failed to utilize human performance error prevention techniques commensurate with the risk of the assigned task to prevent impact to the station.

Violation #2:  A Violation of Technical Specification 5.4.1 was self-revealed when a control rod blade (CRB) disengaged from the lifting tool and gravity fell into an empty cell in the reactor core. The immediate actions taken by licensee personnel were to return equipment to a safe configuration and stop work.

The finding was determined to be more than minor because if left uncorrected it had the potential to lead to a more significant safety concern. Specifically, had the performance deficiency not been corrected and a similar event happened again the CRB could potentially tip over and fall over fuel assemblies rather than on an empty cell. The issue did not need a quantitative assessment and screened as Green. This finding had a cross-cutting aspect in the area of Human Performance, Work Practices, because the licensee staff did not ensure supervisory and management oversight of work activities such that nuclear safety was supported.

Researched by: Bob Meyer